The present invention relates to the immersed inspection of contact lenses and more particularly to devices which expedite positioning a soft contact lens for inspection while the lens is immersed in a liquid.
It is well known that the inspection of soft contact lens parameters is most accurately conducted while a lens is immersed in a liquid. Since soft contact lenses usually contain 35% to 60% water, and the remaining material has a density only slightly different from that of water, it is very time consuming and frequently difficult to accurately position a contact lens immersed in an aqueous medium.
U.S. Pat. No. 3,985,445, issued Oct. 12, 1976, discloses a device for inspecting contact lenses while immersed in a liquid. The patent also discloses apparatus for centering the lens for inspection. The centering apparatus has cylindrical side walls which are adapted to engage or be very slightly larger than the perimeter of the contact lens to be inspected. Since lens diameters differ, a plurality of inserts of varying side wall dimensions are required. The device is adapted to engage a pedestal which is orthogonally movable by means of micrometer screws in order to be aligned on the instrument axis.
An apparatus such as that described in the aforementioned patent is susceptible to distortion of the lens during inspection when the diameter of the apparatus is even slightly less than the lens and inadequate centering when the lens diameter is more than very slightly less than the diameter of the centering apparatus. Also, because of the close proximity of the lens perimeter to the inner wall of the centering apparatus, it is not possible to accurately measure the actual lens diameter in the same inspection device.